Circuit breaker operating device

ABSTRACT

A circuit breaker operating device in which means including a cylinder having a piston connected to the movable contact in the breaking mechanism, a fluid introducing valve for supplying an operating fluid into a main introducing space beneath the piston, and elements for controlling the movement of the fluid introducing valve are disposed within a storage tank containing the operating fluid to eliminate the need for provision of any fluid supply pipe and reduce the pressure loss to a minimum so that the pressure of the operating fluid can be fully effectively utilized for breaking the circuit at a high speed.

D United States Patent 1 1 [111 Hirasawa July 8, 1975 [54] CIRCUITBREAKER OPERATING DEVICE 2,938,346 5/ I960 giratzmuller .r 60/413 3,72,032 3 l97l 60 478 [75] Inventor: Kunlo Hirasawa, Ibaraki, Japan 5erry Asslgneei Hiachi, -r y Japan Primary ExaminerEdgar W. Geoghegan 22Filed: June 24 1974 Attorney, Agent, or Firm-Elliott l. POllOCk [2|]Appl. No.: 482,728

{57] ABSTRACT 30] F i Appfiwtion p Data A; cgrcuit brelakgr opleratingdevice in which nzjeans J 4 [97 n c u mg a cy 1n er avmg a pistonconnecte to t e my 3 Japan 48 823 movable contact in the breakingmechanism, a fluid [52] U 8 Cl 91/461, 60/407, 60/412, introducing valvefor supplying an operating fluid into 7 1 91/469 a main introducingspace beneath the piston, and ele- [5 I 1 Int Cl 11/08 ments forcontrolling the movement of the fluid intro- [58] Fie'ld 413 477 ducingvalve are disposed within a storage tank con- 60/478 1 5 taining theoperating fluid to eliminate the need for provision of any fluid supplypipe and reduce the pressure loss to a minimum so that the pressure ofthe op- [56] References Cited crating fluid can be fully effectivelyutilized for break- UNITED STATES PATENTS ing the circuit at a highspeed. 2,399,294 4/1946 Ray 60/432 2,618,929 11/1952 60/478 21 Claims, 4Drawing Figures CIRCUIT BREAKER OPERATING DEVICE BACKGROUND OF THEINVENTION This invention relates to circuit breaker operating devices,and more particularly to improvements in an operating device of the kindabove described in which a fluid is used as a means for imparting anactuating force for operating a circuit breaker.

The employment of ultra high voltage and the increase in the capacity ofa high power transmission network in recent years has necessitated theuse of circuit breakers having a high voltage rating and a high breakingcapacity. Such a circuit breaker must cut off a current of very largevalue. It is thus necessary to part the circuit breaker contacts at ahigh speed in order to improve the transient stability during breakingthe circuit.

Air blast circuit breakers, double pressure type SP6 gas circuitbreakers and puffer type circuit breakers are commonly known. In anyoneof these known circuit breakers, the operating time of the operatingdevice for moving the movable contact away from the stationary contactin the circuit breaker occupies a relatively great proportion of thelength of time required for breaking the circuit. It is thereforedesirable that the operating device can operate at a highest possiblespeed in order to obtain a satisfactory breaking characteristic.

A conventional circuit breaker operating device has such a structurethat a piston is disposed movably within a stationary cylinder, and thispiston is operatively connected to the movable contact in the circuitbreaker. In breaking the circuit, a pressurized fluid such as air underpressure is supplied to the piston to cause sliding movement of thepiston in the cylinder. This movement of the piston is transmitted tothe movable contact to urge the movable contact away from the stationarycontact thereby attaining the circuit breaking operation.

Such conventional operating device is provided with a control valvedevice consisting of a fluid introducing valve for controlling the flowof the pressurized fluid toward the piston and valve actuating means foractuating this valve by the fluid and a storage tank for the pressurizedfluid which provides the force required for causing sliding movement ofthe piston and driving the valve actuating means. Fluid supply pipes areconnected between the piston and the control valve device and betweenthe control valve device and the storage tank so that the pressurizedfluid in the storage tank can be supplied to the piston through thecontrol valve device and fluid supply pipes.

Such conventional operating device has had a serious defect. In responseto the application of a breaking instruction signal to the circuitbreaker, the fluid introducing valve is opened by the valve actuatingmeans to supply the pressurized fluid to the piston. In the conventionaloperating device, a considerably long time has been required until thepiston starts to move in the circuit breaking direction due to the factthat a dead space exists within the fluid supply pipes and gives rise toa considerable pressure loss. This delay in the operating time has beenone of the principal causes giving rise to an undesirable decline of theoperating characteristic of the circuit breaker.

In a known structure proposed in an effort to obviate such a defect, thefluid supply pipe between the piston and the control valve device iseliminated. In this improved operating device, the fluid introducingvalve is disposed adjacent to one of the openings of the cylinder tonormally hermetically close this opening. According to this structure,the pressurized fluid passing through the fluid introducing valve in theopen position could immediately impart the actuating force to the pistonwithout delay, and thus, the length of time required for the piston tostart to move after the opening of the fluid introducing valve could bereduced. However, in this improved operating device too, the storagetank has been disposed independently of the control valve device, andthe fluid supply pipe between the storage tank and the control valvedevice has been still left as the communication means therebetween. As aresult, the delay in the operating time due to the pressure loss in thisfluid supply pipe has remained still and this has been the neck whichobstructs the desired reduction of the length of time required forbreaking the circuit.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a circuit breaker operating device in which an operating fluidcontained in a storage tank can be directly supplied to a piston withoutany substantial pressure loss so that the device can operate at a highspeed.

Another object of the present invention is to provide a circuit breakeroperating device in which the space within the storage tank containingthe operating fluid is connectably partitioned by a fluid introducingvalve from a main introducing space defined beneath the piston forsupplying the operating fluid to the piston.

Still another object of the present invention is to provide a circuitbreaker operating device in which the fluid introducing valveconnectably partitioning the space within the storage tank from the mainintroducing space is urged to the open position by an actuating pistonwhich is actuated in response to the application of a breakinginstruction signal.

Yet another object of the present invention is to provide a circuitbreaker operating device in which circuit breaking mechanism actuatingmeans including the piston and the cylinder and valve actuating meansincluding the actuating piston are disposed and fixed within the storagetank in axially parallel relation with each other.

A further object of the present invention is to provide a circuitbreaker operating device in which the valve actuating means is rigidlyfixed to the circuit breaking mechanism actuating means and is slidablerelative to the storage tank.

In accordance with one aspect of the present invention, there isprovided a circuit breaker operating device comprising a storage tankfilled with an operating fluid under pressure, circuit breakingmechanism actuating means including a cylinder fixed to said storagetank and having an inlet port disposed within said storage tank, and afirst piston disposed slidably within said cylinder and operativelyconnected to the movable contact in the circuit breaking mechanism; afluid introducing valve disposed to openably close said inlet port ofsaid cylinder so as to permit flow of the operating fluid under pressurecontained in said storage tank into a main introducing space definedbetween said first piston and said cylinder in the position in which itopens said inlet port and to shut off the flow of the operating fluidinto said main introducing space in the position in which it closeshermetically said inlet port; and

valve actuating means including a second piston for controlling themovement of said fluid introducing valve in response to the applicationof a breaking instruction signal.

The operating device of the present invention having a structure asabove described in advantageous in that the operating fluid contained inthe storage tank can be directly supplied to the piston with lowpressure loss without using any fluid supply pipe thereby eliminatingthe pressure loss in the pipe in the prior art device of this kind, sothat the pressure of the operating fluid can be fully effectivelyutilized to shorten the operating time of the operating device. Thepresent invention is further advantageous in that the overall size ofthe device can be reduced due to the fact that the actuating means canbe disposed within the storage tank.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal sectional viewof a first embodiment of the circuit breaker operating device accordingto the present invention in the circuit making position of the circuitbreaker.

FIG. 2 is a view similar to FIG. I but showing the parts in explodedfashion for illustrating the manner of assembling of the device shown inFIG. I.

FIG. 3 is a longitudinal sectional view of a second embodiment of thepresent invention.

FIG. 4 is a section taken on line IVIV in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of thepresent invention will be described with reference to the accompanyingdrawing. FIG. 1 is a longitudinal sectional view of a first embodimentof the circuit breaker operating device of the present invention in anoperating state corresponding to the circuit making position of thecircuit breaker (not shown). Referring to FIG. I, a storage tank 1contains therein an operating fluid such as air under high pressure andis disposed in electrically insulated relation from the circuit breakingmechanism (not shown) of the circuit breaker. A compressor (not shown)is connected to the storage tank 1 through a conduit 51 so as tomaintain the pressure of the high-pressure operating fluid in thestorage tank 1 above a predetermined setting. The high-pressureoperating fluid may be SF6 gas, oil or any other suitable fluid in lieuof the air under high pressure. A cylinder 2 is rigidly fixed at theupper end thereof to a supporting plate 4 bolted to an upper opening ofthe storage tank 1 and is supported to extend downward in FIG. 1 fromthe upper opening of the storage tank I being maintained fluid-tight bya gasket 3. A piston 5 is disposed within the cylinder 2 to be slidablealong the inner wall surface of the cylinder 2 and is provided with aperforation of small diameter 50. The operating device of the presentinvention can operate at a high speed for the reason that the cylinder 2is disposed bodily within the storage tank 1 as shown and the operatingfluid under high pressure contained in the storage tank 1 can bedirectly supplied to the piston 5 without passing through any fluidsupply pipes.

Anoperating rod 6 is mechanically connected to the piston 5 fortransmitting a contact parting force to the movable contact in thecircuit breaking mechanism (not shown). This operating rod 6 is normallyurged downward in FIG. 1 by a contact making means such as a resetspring (not shown). The cylinder 2 and piston 5 constitute an actuatingunit A for actuating the circuit breaking mechanism.

A valve casing 7 is rigidly fixed at the lower end thereof in a loweropening formed in the operating fluid storage tank I. This valve casing7 is disposed opposite to the cylinder 2 and is supported to extendupward from the lower opening of the storage tank 1 by being maintainedfluid-tight by a gasket 8. The valve casing 7 is formed thereinside witha space 17 having an opening communicating with the atmosphere andopenings 7b and 7c communicating with the internal space of the storagetank I. A pilot valve 9 is urged downward in FIG. I by a compressionspring I0 to be pressed against the opening 7b to normally hermeticallyclose the opening 7b. A breaking instruction signal is applied to anenergizing coil 11. In response to the application of the breakinginstruction signal to the energizing coil 11, a trigger valve 12 isurged upward in FIG. I to hermetically close the opening 7a, and at thesame time, the upper end of the trigger valve 12 acts to urge the pilotvalve 9 upward in FIG. 1 against the force of the compression spring 10to open the opening 7b.

An actuating piston 13 is slidably disposed within the upper spaceportion of the valve casing 7 and is normally urged downward in FIG. Iby a compression spring 14. A fluid introducing valve 15 is rigidlyfixed by a nut 40 to the upper end of a piston rod which is fixedintegrally to the actuating piston 13. The compression spring 14 isinterposed between the actuating piston 13 and a spring bearing portion7d of the valve casing 7 so as to normally urge the actuating piston 13and fluid introducing valve 15 downward in FIG. 1. The fluid introducingvalve 15 can make fluid-tight engagement with a valve seat 50 formed atone end of the cylinder 2 so as to prevent flow of the operating fluidunder high pressure in the storage tank 1 into a main introducing space16 beneath the piston 5 through the inlet port of the cylinder 2.

The outer diameter of the fluid introducing valve 15 is selected to besmaller than'that of the actuating piston 13 so that, during the circuitbreaking operation, the fluid introducing valve 15 can be easily urgedto the open position by the pressure of the operating fluid in thestorage tank 1 thereby permitting flow of the operating fluid under highpressure into the main introducing space 16. It will be seen that thepiston rod 130 having the fluid introducing valve 15 fixed thereto isdisposed in axially parallel relation with the axis of of the cylinder 2and that the direction in which the fluid introducing valve 15 is urgedto the open position is the same as the moving direction of the piston 5during the circuit breaking operation of the operating device. By virtueof the above arrangement, the operating device of the present inventioncan operate at a high speed.

The valve casing 7 and various elements disposed within this valvecasing 7 constitute a valve actuating unit B.

In the circuit making position shown in FIG. 1, the upper end 12a of thetrigger valve 12 is spaced apart from the pilot valve 9. In this state,the pilot valve 9 is urged by the compression spring 10 to hermeticallyclose the opening 7b, the opening 7a is not closed by the trigger valve12, and the portion of the space 17 lying between these two openings 70,7b and the actuating piston 13 communicates with the atmosphere. Themain introducing space 16 communicates also with the atmosphere throughthe perforation 5a of the piston 5.

Thus, the piston 5 is held in the lowermost position within the cylinder2 by the force of the reset spring, and the volume of the mainintroducing space 16 in such a state is very small. Although thepressure of the operating fluid in the storage tank 1 acts to force thefluid introducing valve toward the main introducing space 16, thedownward force imparted by the operating fluid to the actuating piston13 fixed to the fluid introducing valve 15 cooperates with the force ofthe compression spring 14 to press the fluid introducing valve 15against the valve seat 50 thereby hermetically closing the inlet port160 against the force of the operating fluid acting upon the fluidintroducing valve 15.

In response to the application of the breaking instruction signal to theenergizing coil 11 in such a state, the trigger valve 12 is urged upwardin FIG. I to hermetically close the opening 7a, and at the same time,the upper end 12a of the trigger valve 12 urges upward the pilot valve 9to open the opening 712. Therefore, the operating fluid in the storagetank I is filled immediately in the space I7 through the opening 7b. Asa result, the relation between the forces acting upon the fluidintroducing valve 15 and actuating piston 13 is reversed. That is, thedownward force acting upon the actuating piston I3 is cancelled by theupward force imparted thereto by the operating fluid supplied throughthe opening 712 and space 17, and the fluid introducing valve 15 isurged upward in FIG. I by the pressure of the operating fluid to openthe inlet port 160 due to the fact that the fluid introducing valve 15has a pressure receiving area which provides a greater force than theforce of the compression spring 14.

As soon as the inlet port 160 is opened, the operating fluid in thestorage tank 1 is filled in the main introducing space 16 to urge thepiston 5 upward in FIG. 1, hence to impart the contact parting force tothe movable contact of the circuit breaker. Due to the fact that theoperating fluid is not filled in the main introducing space 16 by way ofa pipe used in the conventional device but it is directly filled in themain introducing space 16 through the inlet port 160 disposed within thestorage tank 1, an undesirable pressure loss due to such pipe can becompletely eliminated and the pressure of the operating fluid can befully effectively utilized for driving the piston 5.

In the circuit making position shown in FIG. 1, the upper surface of thefluid introducing valve 15 is very slightly spaced from the lowersurface of the piston 5. Thus, in the initial stage of the movement ofthe fluid introducing valve 15 in the valve opening direction, the fluidintroducing valve 15 abuts the piston 5 to cease the movement thereoftemporarily. Therefore, the gap initially formed between the fluidintroducing valve 15 and the valve seat 50 is not so large. However, dueto the fact that the initial volume of the main introducing space 16 isvery small, the gap initially formed between the fluid introducing valve15 and the valve seat 50 is large enough to ensure instantaneous fillingof the operation fluid in the main introducing space 16. When the piston5 starts to move upward in FIG. 1 by the pressure of the operating fluidfilled in this space 16, the fluid introducing valve 15 can also moveupward in FIG. I, with the result that the gap formed between the fluidintroducing valve 15 and the valve seat 50 increases gradually. Thus,the operating fluid can be filled in the main introducing space 16 witha low pressure loss to impart a desirable driving force to the piston 5.

After impartation of sufficient inertia to the piston 5 by the pressureof the operating fluid, the breaking instruction signal applied to theenergizing coil II disappears and the trigger valve 12 is restored tothe position shown in FIG. 1 by a resetting means (not shown) to causedischarge of the operating fluid in the space l7 to the atmospherethrough the opening 7a. Therefore, the sum of the downward force actingupon the actuating piston 13 and the force of the compression spring 14overcomes the upward force acting upon the fluid introducing valve 15again, and the fluid introducing valve 15 is urged downward in FIG. 1 tohermetically close the inlet port 160 again. The valve actuating unit Bis restored to the circuit making position shown in FIG. I.

Although the supply of the operating fluid from the storage tank I isceased in the above state, the piston 5 moves further upward by inertiato reach the circuit breaking position for parting the movable contactand is mechanically locked in such position by a locking means (notshown). This completes the circuit breaking operation of the circuitbreaker. The operating fluid filled in the main introducing space 16 isrelatively gradually discharged to the atmosphere through theperforation 5a bored in the piston 5 so as to eliminate an undesirablereaction force which may be imparted to the circuit making means duringsubsequent circuit making operation by the piston 5.

In making the circuit again, the locking means is released and theaction of, for example, the reset spring in which the force isaccumulated during the circuit breaking operation is utilized to bringthe movable contact into contact with the stationary contact. At thesame time, the piston 5 is urged downward in FIG. I to be restored tothe position shown in FIG. I. The piston 5 can move smoothly in theabove direction due to the fact that the operating fluid filled in themain introducing space 16 has been discharged through the perforation 5aof the piston 5 and the pressure in this space 16 is substantially equalto the atmospheric pressure. The perforation 5a of the piston 5 actsalso to alleviate the pressure rise occurring in the main introducingspace 16 during the movement of the piston 5 toward the originalposition shown in FIG. 1. This pressure rise is negligible for thereason that the movement of the piston Sin the circuit making operationis generally slower than that in the circuit breaking operation. Theperforation Sa of the piston 5 may be eliminated to maintain the piston5 in the circuit breaking position by the operating fluid in the storagetank 1, and a valve means acting to discharge the operating fluid in themain introducing space 16 in response to the application of a makinginstruction signal to the reset spring may be provided so as toeliminate an undesirable reaction force which may be imparted to thepiston 5 as soon as the circuit making operation is started.

The operating fluid is in no way limited to air under high pressure andany other suitable fluid may be used in lieu of air. In this lattercase, it is necessary to provide a collecting vessel for collecting theoperating fluid discharged from the opening and the perforation 50.

In the first embodiment above described, the pressure of the operatingfluid filled in the space 17 is utilized to drive the fluid introducingvalve 15. However,

the structure may be such that the force driving the fluid introducingvalve 15 can be obtained by discharging a portion of the operating fluidto the atmosphere in response to the application of the circuit breakinginstruction to the energizing coil ll. It will be understood that thepresent invention is featured by the fact that the inlet port 16a forfilling the operating fluid in the main introducing space l6 for drivingthe piston is disposed within the operating fluid storage tank 1. Inother words, the present invention is featured by the fact that the mainintroducing space 16 is partitioned directly by the fluid introducingvalve from the space within the storage tank 1 containing the operatingfluid which drives the piston 5. Thus, the circuit breaker operatingdevice according to the present invention can operate at a high speedwithout any substantial pressure loss in contrast to a large pressureloss which has been encountered with prior art devices using fluidsupply pipes. Further, due to the fact that the fluid introducing valve15 in the first embodiment above described is adapted to move in thesame direction as the moving direction of the piston S, the initialvolume of the main introducing space 16 in the circuit making positionshown in FIG. 1 can be made very small so that the dead space owing tothis space 16 can be reduced and the length of time required for circuitbreaking operation can be shortened. More precisely, if the fluidintroducing valve 15 were arranged to move in a direction perpendicularto the direction of movement of the piston 5, the main introducing space16 would have a maximum volume corresponding to the stroke required forthe fluid introducing valve 15 to move until the circuit breakingoperation is completed, and this would result in the defect that a largedead space is formed. The present invention obviates such a defect andthe volume of the main introducing space 16 can be reduced to a minimum.

The circuit breaker operating device shown in FIG. 1 can be assembled ina manner as shown in FIG. 2.

At first, the valve actuating unit B is inserted in the lower opening ofthe storage tank 1 and fixed in the predetermined position. Then, thecylinder 2 is inserted in the upper opening of the storage tank 1 inaxially parallel relation with the valve actuating unit B, and the fluidintroducing valve 15 is connected to the actuating piston 13 by the nut40 within the cylinder 2. Subsequently, the piston 5 is disposedslidably within the cylinder 2, and the supporting plate 4 is fixed tothe storage tank 1 to support the cylinder 2 in the predeterminedposition.

It will be seen that the cylinder 2 has an open internal space whichcommunicates with the atmosphere surrounding the storage tank 1, and thepiston 5 is disposed in this internal space of the cylinder 2. By virtueof such structure, the operating device can be very easily assembled inspite of the fact that the storage tank I has a narrow internal space.

FIGS. 3 and 4 show a second embodiment of the circuit breaker operatingdevice according to the present invention. This second embodiment isgenerally similar in construction to the first embodiment. Thus, likeparts are designated by adding 100 to the corresponding ones of thefirst embodiment and any detailed description as to such parts will notbe given herein.

In the second embodiment, an actuating piston 113 to which a fluidintroducing valve 115 is fixed has a valve portion 152 so that thisactuating piston 113 can act also as a fluid shut-off valve. in thecircuit making position in which the fluid introducing valve is influid-tight engagement with a valve seat formed in a cylinder 102, thevalve portion 152 of the actuating piston H3 is also in fluid-tightengagement with a valve seat 153 fixed to a valve casing 107. Relativelyloose fluid-tightness is allowable between the actuating piston 113 andthe inner wall of the valve casing 107 in the circuit making position ofthe operating device due to the fact that the actuating piston ll3itself acts as the fluid shut-off valve. In spite of this advantage,however, such difficulty arises that, in the circuit making position ofthe operating device. satisfactory fluid-tight engagement must be alwaysmaintained between the fluid introducing valve 115 and the valve seat150 and between the actuating piston 113 and the valve seat I53. Thisdefect becomes marked when thermal expansion occurs in the individualparts.

More precisely. if an actuating unit A for actuating the circuitbreaking mechanism and an actuating unit B for actuating the fluidintroducing valve 115 were fixed in a storage tank 101 in a manner asshown in the first embodiment, the fluid introducing valve [15hermetically closing the inlet port 1160 of the cylinder 102 would notmake satisfactory fluid-tight engagement with the valve seat 150 andmal-operation of the circuit breaker would result due to the fact thatthe units A and B and the storage tank 101 may make thermal expansion ofdifferent degrees depending on the materials and ambient conditions.

A suitable means is provided in the second embodiment of the presentinvention in order to obviate such a defect. This means comprises aplurality of connecting members 20 as shown in FIGS. 3 and 4 whichconnect rigidly the upper end of the valve casing 107 in the valveactuating unit B to the cylinder 102 in the circuit breaking mechanismactuating unit A. The number and thickness of these connecting members20 are selected so as not to obstruct the flow of the operating fluidinto a main introducing space 116.

The circuit breaking mechanism actuating unit A and the valve actuatingunit B are disposed opposite to each other in axially parallel relation,and the valve actuating unit B is disposed so as to be slidable in theaxial direction thereof relative to the storage tank 101 while beingmaintained in fluid-tight relation with the storage tank 101 by means ofa gasket 108. Thus, the difference between the coefficients of thermalexpansion of the units A, B and the storage tank 101 can be absorbed bythe sliding movement of the valve actuating unit B, and mal-operation ofthe circuit breaker due to incomplete fluid-tight engagement between thefluid introducing valve 115 and the valve seat 150 can be prevented.

The term axially parallel relation" is used to denote such arelationship that the axis of the valve actuating unit B registers withor is suitably parallelly displaced from the axis of the cylinder 102which is the stationary part of the circuit breaking mechanism actuatingunit A. In other words, the cylinder 102 and the valve actuating unit Bare mechanically connected to each other by the connecting members 20 insuch a relationship that the valve actuating unit B is movable in thesame axial direction as that of the cylinder 102 when thermal expansionoccurs. Therefore, the force tending to move the fluid introducing valve115 away from the valve seat 150 due to the different coefiicients ofthermal expansion of the units A, B and storage tank is absorbed tocause corresponding downward movement of the valve actuating unit B.

it will be understood from the foregoing detailed description that, inthe present invention, the inlet port 16a for the operating fluid isdisposed within the operating fluid storage tank 1, and the fluidintroducing valve is disposed to partition directly the space within thestorage tank 1 containing the operating fluid from the main introducingspace 16 into which the operating fluid is filled during the circuitbreaking operation for imparting the contact parting force to themovable contact of the circuit breaker. Thus, the operating fluid can befilled in the main introducing space 16 as soon as the fluid introducingvalve 15 is actuated by the valve actuating unit B. Further, due to thefact that no fluid supply pipes exist in this portion, no pressure lossoccurs and the operating fluid in the storage tank 1 can be fullyeffectively utilized so as to shorten the length of time required foractuating the piston 5.

Further, in the present invention, the main introducing space 16 isdefined between the cylinder 2 and the piston 5 imparting the contactparting force to the mov able contact of the circuit breaker, and theinlet port 16a of the cylinder 2 having the main introducing space 16therein is openably closed by the fluid introducing valve 15. Thecylinder 2 in the circuit breaking mechanism actuating unit A isdisposed opposite to and mechanically connected with the valve actuatingunit B in axially parallel relation, and the valve actuating unit B isarranged to be slidable in the axial direction thereof relative to thestorage tank 1 while being maintained in fluid-tight relation with thestorage tank 1. Thus, even when the circuit breaking mechanism actuatingunit A, valve actuating unit B and storage tank 1 have differentcoefficients of thermal expansion, the force tending to move the fluidintroducing valve 15 away from the associated valve seat can be absorbedby the slidable connection to prevent mal-operation of the circuitbreaker due to incomplete fluid-tight engagement of the fluidintroducing valve 15 with the valve seat. Furthermore, the overall sizeof the circuit breaker can be reduced due to the fact that the entiretyor portions of the operating device can be disposed within the storagetank 1.

I claim:

1. A circuit breaker operating device comprising a storage tank filledwith an operating fluid under pressure; circuit breaking mechanismactuating means including a cylinder fixed to said storage tank andhaving an inlet port disposed within said storage tank, and a firstpiston disposed slidably within said cylinder and operatively connectedto the movable contact in the circuit breaking mechanism; a fluidintroducing valve disposed to openably close said inlet port of saidcylinder so as to permit flow of the operating fluid under pressurecontained in said storage tank into a main introducing space definedbetween said first piston and said cylinder in the position in which itopens said inlet port and to shut off the flow of the operating fluidinto said main introducing space in the position in which it closeshermetically said inlet port; and valve actuating means including asecond piston for controlling the movement of said fluid introducingvalve in response to the application of a breaking instruction signal.

2. A circuit breaker operating device comprising a storage tankconnected to a compressor by a conduit and containing an operating fluidof predetermined pressure therein; circuit breaking mechanism actuatingmeans including a cylinder fixed to said storage tank and having aninlet port disposed within said storage tank, and a first pistondisposed slidably within said cylinder and operatively connected to themovable contact in the circuit breaking mechanism; a fluid introducingvalve disposed to openably close said inlet port of said cylinder so asto permit flow of the operating fluid under pressure contained in saidstorage tank into a main introducing space defined between said firstpiston and said cylinder in the position in which it opens said inletport and to shut off the flow of the operating fluid into said mainintroducing space in the position in which it closes hermitically saidinlet port; and valve actuating means rigidly fixed to said storage tankin fluid-tight relation, said valve actuating means including a secondpiston for controlling the movement of said fluid introducing valve inresponse to the application of a breaking instruction signal.

3. A circuit breaker operating device as claimed in claim 2, whereinsaid first piston and said fluid introducing valve are moved in the samedirection during the circuit breaking operation, and said first pistonis very slightly spaced from said fluid introducing valve in the circuitmaking position so that said main introducing space has a small initialvolume in such position.

4. A circuit breaker operating device as claimed in claim 3, whereinsaid first piston is provided with a perforation of small diameter sothat the operating fluid within said main introducing space can bedischarged through said perforation after the circuit breakingoperation.

S. A circuit breaker operating device as claimed in claim 3, whereinsaid valve actuating means includes a valve casing slidably receivingsaid second piston therein, and said second piston is fixed to saidfluid introducing valve.

6. A circuit breaker operating device as claimed in claim 5, whereinsaid second piston is normally urged by a compression spring in aclosing direction of said fluid introducing valve, the direction ofmovement of said second piston for urging said fluid introducing valveto the open position is the same as the direction of movement of saidfirst piston during the circuit breaking operation by being actuated bythe operating fluid supplied from said storage tank through said fluidintroducing valve, and said fluid introducing valve abuts said firstpiston in the initial stage of movement thereof in the opening directionto define a limited gap between it and the valve seat, said fluidintroducing valve being then moved to its'full open position with thesubsequent movement of said first piston.

7. A circuit breaker operating device as claimed in claim 6, wherein themovement of said second piston is controlled by the operating fluidcontained in said storage tank.

8. A circuit breaker operating device as claimed in claim 7, whereinsaid valve casing is formed with a space having an opening communicatingwith the atmosphere and another opening communicating with the spacewithin said storage tank, and said openings are opened and closed by apilot valve and a trigger valve respectively so that the operating fluidin said storage tank can actuate said second piston.

9. A circuit breaker operating device as claimed in claim 8, whereinsaid opening communicating with the space within said storage tank isopened and closed by said pilot valve normally urged in a closingdirection by a compression spring, said opening communicating with theatmosphere is opened and closed by said trigger valve having anenergizing coil actuated in response to the application of the breakinginstruction signal. and one end portion of said trigger valve acts tourge said pilot valve to the open position against the force of saidcompression spring.

10. A circuit breaker operating device as claimed in claim 7, whereinthe outer diameter of said fluid intro ducing valve is selected to besmaller than that of said second piston.

11. A circuit breaker operating device as claimed in claim 10, whereinsaid second piston is provided with a valve portion which can be broughtinto fluid-tight engagement with a valve seat fixed to said valvecasing.

12. A circuit breaker operating device comprising a storage tankconnected to a compressor by a conduit and containing an operating fluidof predetermined pressure therein; circuit breaking mechanism actuatingmeans including a cylinder fixed to said storage tank and having aninlet port disposed within said storage tank, and a first pistondisposed slidably within said cylinder and operatively connected to themovable contact in the circuit breaking mechanism; a fluid introducingvalve disposed to openably close said inlet port of said cylinder so asto permit flow of the operating fluid under pressure contained in saidstorage tank into a main introducing space defined between said firstpiston and said cylinder in the position in which it opens said inletport and to shut off the flow of the operating fluid into said mainintroducing space in the position in which it closes hermetically saidinlet port; and valve actuating means including a valve casing, and asecond piston disposed slidably within said valve casing and fixedintegrally to said fluid introducing valve for controlling the movementof said fluid introducing valve in response to the application of abreaking instruction signal.

13. A circuit breaker operating device as claimed in claim 12, whereinsaid valve casing in said valve actuating means is disposed slidablerelative to said storage tank and is rigidly connected by connectingmembers to said cylinder in said breaking mechanism actuating means.

14. A circuit breaker operating device as claimed in claim 13, wherein agasket is provided between said valve casing and said storage tank tomaintain fluidtight engagement therebetween.

15. A circuit breaker operating device as claimed in claim 13, whereinsaid first piston is provided with a perforation of small diameter sothat the operating fluid within said main introducing space can bedischarged through said perforation after the circuit breakingoperation.

16. A circuit breaker operating device as claimed in claim 13, whereinsaid second piston is normally urged by a compression spring in aclosing direction of said fluid introducing valve, the direction ofmovement of said second piston for urging said fluid introducing valveto the open position is the same as the direction of movement of saidfirst piston during the circuit breaking operation by being actuated bythe operating fluid supplied from said storage tank through said fluidintroducing valve, and said fluid introducing valve abuts said firstpiston in the initial stage of movement thereof in the opening directionto define a limited gap between it and the valve seat, said fluidintroducing valve being then moved to its full open position with thesubsequent movement of said first piston.

17. A circuit breaker operating device as claimed in claim 16, whereinthe movement of said second piston is controlled by the operating fluidcontained in said storage tank.

18. A circuit breaker operating device as claimed in claim 17, whereinsaid valve casing is formed with a space having an opening communicatingwith the atmosphere and another space communicating with the spacewithin said storage tank, and said openings are opened and closed by apilot valve and a trigger valve respectively so that the operating fluidin said storage tank can actuate said second piston.

19. A circuit breaker operating device as claimed in claim 18, whereinsaid opening communicating with the space within said storage tank isopened and closed by said pilot valve normally urged in a closingdirection by a compression spring, said opening communicating with theatmosphere is opened and closed by said trigger valve having anenergizing coil actuated in response to the application of the breakinginstruction signal, and one end portion of said trigger valve acts tourge said pilot valve to the open position against the force of saidcompression spring.

20. A circuit breaker operating device as claimed in claim 17, whereinthe outer diameter of said fluid introducing valve is selected to besmaller than that of said second piston.

21. A circuit breaker operating device as claimed in claim 20, whereinsaid second piston is provided with a valve portion which can be broughtinto fluid-tight engagement with a valve seat fixed to said valvecasing.

1. A circuit breaker operating device comprising a storage tank filledwith an operating fluid under pressure; circuit breaking mechanIsmactuating means including a cylinder fixed to said storage tank andhaving an inlet port disposed within said storage tank, and a firstpiston disposed slidably within said cylinder and operatively connectedto the movable contact in the circuit breaking mechanism; a fluidintroducing valve disposed to openably close said inlet port of saidcylinder so as to permit flow of the operating fluid under pressurecontained in said storage tank into a main introducing space definedbetween said first piston and said cylinder in the position in which itopens said inlet port and to shut off the flow of the operating fluidinto said main introducing space in the position in which it closeshermetically said inlet port; and valve actuating means including asecond piston for controlling the movement of said fluid introducingvalve in response to the application of a breaking instruction signal.2. A circuit breaker operating device comprising a storage tankconnected to a compressor by a conduit and containing an operating fluidof predetermined pressure therein; circuit breaking mechanism actuatingmeans including a cylinder fixed to said storage tank and having aninlet port disposed within said storage tank, and a first pistondisposed slidably within said cylinder and operatively connected to themovable contact in the circuit breaking mechanism; a fluid introducingvalve disposed to openably close said inlet port of said cylinder so asto permit flow of the operating fluid under pressure contained in saidstorage tank into a main introducing space defined between said firstpiston and said cylinder in the position in which it opens said inletport and to shut off the flow of the operating fluid into said mainintroducing space in the position in which it closes hermitically saidinlet port; and valve actuating means rigidly fixed to said storage tankin fluid-tight relation, said valve actuating means including a secondpiston for controlling the movement of said fluid introducing valve inresponse to the application of a breaking instruction signal.
 3. Acircuit breaker operating device as claimed in claim 2, wherein saidfirst piston and said fluid introducing valve are moved in the samedirection during the circuit breaking operation, and said first pistonis very slightly spaced from said fluid introducing valve in the circuitmaking position so that said main introducing space has a small initialvolume in such position.
 4. A circuit breaker operating device asclaimed in claim 3, wherein said first piston is provided with aperforation of small diameter so that the operating fluid within saidmain introducing space can be discharged through said perforation afterthe circuit breaking operation.
 5. A circuit breaker operating device asclaimed in claim 3, wherein said valve actuating means includes a valvecasing slidably receiving said second piston therein, and said secondpiston is fixed to said fluid introducing valve.
 6. A circuit breakeroperating device as claimed in claim 5, wherein said second piston isnormally urged by a compression spring in a closing direction of saidfluid introducing valve, the direction of movement of said second pistonfor urging said fluid introducing valve to the open position is the sameas the direction of movement of said first piston during the circuitbreaking operation by being actuated by the operating fluid suppliedfrom said storage tank through said fluid introducing valve, and saidfluid introducing valve abuts said first piston in the initial stage ofmovement thereof in the opening direction to define a limited gapbetween it and the valve seat, said fluid introducing valve being thenmoved to its full open position with the subsequent movement of saidfirst piston.
 7. A circuit breaker operating device as claimed in claim6, wherein the movement of said second piston is controlled by theoperating fluid contained in said storage tank.
 8. A circuit breakeroperating device as claimed in claim 7, wherein said Valve casing isformed with a space having an opening communicating with the atmosphereand another opening communicating with the space within said storagetank, and said openings are opened and closed by a pilot valve and atrigger valve respectively so that the operating fluid in said storagetank can actuate said second piston.
 9. A circuit breaker operatingdevice as claimed in claim 8, wherein said opening communicating withthe space within said storage tank is opened and closed by said pilotvalve normally urged in a closing direction by a compression spring,said opening communicating with the atmosphere is opened and closed bysaid trigger valve having an energizing coil actuated in response to theapplication of the breaking instruction signal, and one end portion ofsaid trigger valve acts to urge said pilot valve to the open positionagainst the force of said compression spring.
 10. A circuit breakeroperating device as claimed in claim 7, wherein the outer diameter ofsaid fluid introducing valve is selected to be smaller than that of saidsecond piston.
 11. A circuit breaker operating device as claimed inclaim 10, wherein said second piston is provided with a valve portionwhich can be brought into fluid-tight engagement with a valve seat fixedto said valve casing.
 12. A circuit breaker operating device comprisinga storage tank connected to a compressor by a conduit and containing anoperating fluid of predetermined pressure therein; circuit breakingmechanism actuating means including a cylinder fixed to said storagetank and having an inlet port disposed within said storage tank, and afirst piston disposed slidably within said cylinder and operativelyconnected to the movable contact in the circuit breaking mechanism; afluid introducing valve disposed to openably close said inlet port ofsaid cylinder so as to permit flow of the operating fluid under pressurecontained in said storage tank into a main introducing space definedbetween said first piston and said cylinder in the position in which itopens said inlet port and to shut off the flow of the operating fluidinto said main introducing space in the position in which it closeshermetically said inlet port; and valve actuating means including avalve casing, and a second piston disposed slidably within said valvecasing and fixed integrally to said fluid introducing valve forcontrolling the movement of said fluid introducing valve in response tothe application of a breaking instruction signal.
 13. A circuit breakeroperating device as claimed in claim 12, wherein said valve casing insaid valve actuating means is disposed slidable relative to said storagetank and is rigidly connected by connecting members to said cylinder insaid breaking mechanism actuating means.
 14. A circuit breaker operatingdevice as claimed in claim 13, wherein a gasket is provided between saidvalve casing and said storage tank to maintain fluid-tight engagementtherebetween.
 15. A circuit breaker operating device as claimed in claim13, wherein said first piston is provided with a perforation of smalldiameter so that the operating fluid within said main introducing spacecan be discharged through said perforation after the circuit breakingoperation.
 16. A circuit breaker operating device as claimed in claim13, wherein said second piston is normally urged by a compression springin a closing direction of said fluid introducing valve, the direction ofmovement of said second piston for urging said fluid introducing valveto the open position is the same as the direction of movement of saidfirst piston during the circuit breaking operation by being actuated bythe operating fluid supplied from said storage tank through said fluidintroducing valve, and said fluid introducing valve abuts said firstpiston in the initial stage of movement thereof in the opening directionto define a limited gap between it and the valve seat, said fluidintroducing valve being then moved to its full open position wIth thesubsequent movement of said first piston.
 17. A circuit breakeroperating device as claimed in claim 16, wherein the movement of saidsecond piston is controlled by the operating fluid contained in saidstorage tank.
 18. A circuit breaker operating device as claimed in claim17, wherein said valve casing is formed with a space having an openingcommunicating with the atmosphere and another space communicating withthe space within said storage tank, and said openings are opened andclosed by a pilot valve and a trigger valve respectively so that theoperating fluid in said storage tank can actuate said second piston. 19.A circuit breaker operating device as claimed in claim 18, wherein saidopening communicating with the space within said storage tank is openedand closed by said pilot valve normally urged in a closing direction bya compression spring, said opening communicating with the atmosphere isopened and closed by said trigger valve having an energizing coilactuated in response to the application of the breaking instructionsignal, and one end portion of said trigger valve acts to urge saidpilot valve to the open position against the force of said compressionspring.
 20. A circuit breaker operating device as claimed in claim 17,wherein the outer diameter of said fluid introducing valve is selectedto be smaller than that of said second piston.
 21. A circuit breakeroperating device as claimed in claim 20, wherein said second piston isprovided with a valve portion which can be brought into fluid-tightengagement with a valve seat fixed to said valve casing.